Amino nitrile intermediate for the preparation of 2-hydroxyethyl iminodiacetic acid

ABSTRACT

A novel intermediate useful in the synthesis of 2-hydroxyethyl iminodiacetic acid is disclosed. The intermediate can be formed by contacting 2-hydroxyethyl amine with glycolonitrile to form an aminonitrile which can be hydrolyzed and contacted with additional glycolonitrile to form the nitrile intermediate which can be converted to 2-hydroxylethyl iminodiacetic acid via hydrolysis.

This application is a division of 08/741,592 filed on Oct. 31, 1996, nowU.S. Pat. No. 5,726,341 which claims benefit of U.S. ProvisionalApplication No. 60/008,565 filed December 13, 1995.

BACKGROUND OF THE INVENTION

The present invention is to novel intermediates useful in the synthesisof 2-hydroxyethyl iminodiacetic acid.

Chelants or chelating agents are compounds which formcoordinate-covalent bonds with a metal ion to form chelates. Chelatesare coordination compounds in which a central metal atom is bonded totwo or more other atoms in at least one other molecule or ion, called aligand, such that at least one heterocyclic ring is formed with themetal atom as part of each ring.

Chelating agents for metal ions, such as calcium, magnesium, iron, andmanganese, are required for a wide range of technical fields. Examplesof fields of application and end-uses are detergents, in electroplating,in water treatment, photography, textile industry, paper industry andalso various uses in pharmaceuticals, cosmetics, foodstuffs and plantnutrition. Some of these activities may result in the chelating agentsentering the environment. For example, agricultural uses or use indetergents may result in measurable quantities of the chelants in water.

As chelants may enter the environment from various uses, it is desirableto have chelants that would readily degrade after use. It would beparticularly advantageous to have a chelant which is biodegradable, thatis, susceptible to degradation by microbes which are generally naturallypresent in environments into which the chelants may be introduced.

Iminodiacetic acid derivatives are known to possess metal sequesteringproperties. U.S. Pat. No. 5,051,212 discloses that iminodiacetic acid,when combined with organic solvents, provide very good results in termsof soil removal from hard surfaces. The use of iminodiacetic acidderivatives in aqueous compositions for cleaning hard surfaces isreported in PCT Application No. WO 94/12606. The iminodiaetic acidderivatives in WO 94/12606 are also reported to have good biodegradablecharacteristics.

SUMMARY OF THE INVENTION

The present invention provides a novel composition of matter useful asan intermediate in the synthesis of 2-hydroxyethyl iminodiacetic acid(HEIDA). Specifically, the novel intermediate is a compound representedby the ##STR1## formula

wherein X represents hydrogen, an alkali metal or alkaline earth metal.

In another aspect, the invention is to a process for producing HEIDA bybasic hydrolysis of the above-noted intermediate.

The present invention also relates to hard surface cleaning compositionscontaining HEIDA in an aqueous system. The hard surface cleaningcompositions provide a method for cleaning hard surfaces comprisingcontacting a hard surface with a composition containing HEIDA andremoving a portion of the composition from the hard surface.

DETAILED DESCRIPTION OF THE INVENTION

Starting materials for making the novel intermediate of the presentinvention include 2-hydroxyethylamine and glycolonitrile. A suitablereaction scheme for synthesis of the novel intermediate is shown inScheme I. In step (a) 2-hydroxyethylamine is contacted withglycolonitrile to form N-cyanomethylamino-2-ethanol.

The molar ratio of 2-hydroxyethylamine to glycolonitrile is generallyabout 1:1 with a slight excess of glycolonitrile preferred. ##STR2##

The hydrolysis of (1) with base gives N-carboxymethylamino-2-ethanol(II). Compound (II) is then reacted with additional glycolonitrile toform N-carboxymethyl-N-cyanomethylamino-2-ethanol (III). The molar ratioof (II) to glycolonitrile is generally about 1:1. In the abovereactions, hydrogen cyanide and formaldehyde can be substituted forglycolonitrile.

Compound (III) is useful as an intermediate for the production of HEIDA.Specifically, compound (III) is hydrolyzed using a base such as sodiumhydroxide to give the alkali metal salt of HEIDA. Hydrolysis of thenitrile group proceeds through the amide intermediate as depicted bystructure IIIa in Scheme I on to the carboxymethyl group, and liberatesammonia which can be conveniently removed from the hydrolysis solution.

In Scheme I, the reaction is shown as occurring in the presence ofaqueous sodium hydroxide. The above reactions may be carried out in thepresence of other bases capable of hydrolyzing the nitrilefunctionality. Examples of other bases include alkali and alkaline earthmetal hydroxides. Preferably sodium or potassium hydroxide are used inthe above reaction scheme.

In addition to bases, the nitrile functionality can be hydrolyzed usingstrong acids such as hydrochloric or sulfuric acid. In this case, theammonium salt of the respective acid is obtained as a by-product.

While reaction Scheme I shows the addition of one mole equivalent ofbase per mole of nitrile functionality, excess molar amounts of base canbe used.

Preferably the glycolonitrile reaction steps (a) and (c) are carried outat a temperature from about 0° to about 100° C., preferably from about15° to about 65° C. The hydrolysis of (I) and (III) is generally done ata temperature from about 0° to about 120° C. Preferably the hydrolysisstep (d) is done at a temperature from about 20° to about 105° C.

The hydrolysis of (III) to HEIDA results in a conversion in excess of 90percent. Although Scheme I indicates that the production of III andHEIDA are done in step reactions, the production of IV can beaccomplished by adding glycolonitrile to an alkaline solution of2-hydroxyethylamine at a temperature to achieve alkaline hydrolysis. Inthis procedure, intermediate III is rapidly converted to IV.

HEIDA is a chelant which will biodegrade in both the semi-continuousactivated sludge test (ASTM D-2667) and the modified Sturm test (OECD301B). In the activated sludge test, a standardized sludge containingmunicipal waste treatment plant organisms is used to biodegrade thechelant in the presence of metal ions representative of those found inthe environment. Such a test simulates the environment encountered in amunicipal waste treatment plant for screening the inherentbiodegradability of non-volatile water-soluble compounds.

The modified Sturm test, in a similar manner contacts the chelant to astandardized culture of microorganisms. The evolution of carbon dioxideis used as a basis for determining microbial degradation when the testchelant is used as the sole carbon source.

HEIDA as a chelant is useful, for instance, in food products vulnerableto metal-catalyzed spoilage or discoloration; in cleaning and launderingproducts for removing metal ions, e.g. from hard water that may reducethe effectiveness, appearance, stability, rinsibility, bleachingeffectiveness, germicidal effectiveness or other property of thecleaning agents; in personal care products like creams, lotions,deodorants and ointments to avoid metal-catalyzed oxidation andrancidity, turbidity, reduced shelf-like and the like; and in pulp andpaper processing to enhance or maintain bleaching effectiveness. HEIDAcan also be used in pipes, vessels, heat exchanges, evaporators, filtersand the like to avoid or remove scaling; in pharmaceuticals; in metalworking; in textile preparation, desizing, scouring, bleaching, dyeingand the like; in agriculture as in chelated micronutrients orherbicides; in polymerization or stabilization of polymers; inphotography, e.g. in developers or bleaches; and in the oil field suchas for drilling, production, recovery, hydrogen sulfide abatement andthe like. The amount of chelating agent employed in the above notedapplications are known in the art.

The use of HEIDA is particularly advantageous for use in cleaningcompositions suitable for hard-surface cleaning, such as certainautomatic dishwashing agents and kitchen or bathroom soil removal,especially calcium soap removal from bathtub surfaces. HEIDA isparticularly advantageous for use in hard-surface cleaners for use incontrol of alkaline-earth metals, particularly calcium, and inpreventing scaling. When used in hard-surface cleaners, HEIDA generallyconstitutes at least about 0.1 weight percent of the cleaner andtypically less than about 25 percent. Preferably the hard-surfacecleaner contains about 0.1 to about 15 percent HEIDA, and morepreferably about 0.5 to about 5 percent.

In addition to being biodegradable, it has been found that HEIDA can beused in hard-surface cleaners free of organic solvents. This isparticularly advantageous in that cleaning can be done without theconcern for release of organic solvent into the environment.

Hard-surface cleaning compositions containing HEIDA are usually at analkaline pH with a range of about 8 to about 14. Preferably the pH ofthe cleaning composition is from about 9 to about 13, and morepreferably from about 10 to about 12.

In addition to HEIDA, hard surface cleaners of the present invention canoptionally contain additional additives well known in the art. Forexample, surface-active agents, are beneficial in a hard-surfacecleaner.

Such surface active agents include water-soluble surfactants such assynthetic anionic, nonionic, cationic, amphoteric and zwitterionicsurfactants and mixtures thereof. Exemplary surfactants include thealkyl benzene sulfates and sulfonates, paraffin sulfonates, olefinsulfonates, alkoxylated (especially ethoxylated) alcohols and alkylphenols, amine oxides, sulfonates of fatty acids and of fatty acidesters, and the like, which are known in the detergency art. Preferably,such surfactants contain an alkyl group in about the C₁₀ -C₁₈ range.Anionic surfactants are commonly used in the form of their sodium,potassium or triethanolammonium salts. The nonionics advantageouslycontain from about 3 to about 17 ethylene oxide groups per mole ofhydrophobic moiety. Representative cationic surfactants includequaternary ammonium compounds such as ditallow dimethyl ammoniumchloride and are preferably used in combination with nonionicsurfactants. Preferred in the composition are about C₁₂ -Cl₁₆ alkylbenzene sulfonates, about C₁₂ -C₁₈ paraffin-sulfonates and theethoxylated alcohols of the formula RO(CH₂ -CH₂ O)n, with R being a C₁₂-C₁₅ alkyl chain and n being a number from 6 to 10, and the ethoxylatedalcohol sulfates of formula RO-(CH₂ -CH20)n-SO₃ M, with R being a C₁₂-C₁₈ alkyl chain, is a number from about 2 to about 8, and M is H or analkali metal ion.

Anionic surfactants are advantageously present at levels from about 0.3percent to about 8 percent of the hard surface cleaning composition.Nonionic surfactants, are preferably used at levels between about 0.1percent to about 6 percent by weight of the composition. Mixtures ofsurfactants are also useful.

Other optional ingredients include detergent buildeis, within the skillin the art, including nitrilotriacetate (NTA), polycarboxylates,citrates, water-soluble phosphates such as tri-polyphosphate and sodiumortho-and pyro-phosphates, silicates, ethylene diamine tetraacetate(EDTA), amino-polyphosphonates, phosphates and mixtures thereof.

Other optional additives for the hard surface cleaners include detergenthydrotropes. Exemplary hydrotropes include urea, monoethanolamine,diethanolamine, triethanolamine and the sodium, potassium, ammonium andalkanol ammonium salts of xylene-, toluene-, ethylbenzene-andisopropyl-benzene sulfonates.

The hard-surface cleaning compositions of the invention also optionallycontain an abrasive material. The abrasive materials includewater-insoluble, non-gritty materials known for their relatively mildabrasive properties. It is preferred that the abrasives used herein notbe undesirably "scratchy". Abrasive materials having a Mohs hardness ofno more than about 7 are preferred; while abrasives having a Mohshardness of no more than about 3, are useful to avoid scratches onfinishes such as aluminum or stainless steel. Suitable abrasives includeinorganic materials, especially such materials as calcium carbonate anddiatomaceous earth, as well as materials such as Fuller's earth,magnesium carbonate, China clay, actapulgite, calcium hydroxyapatite,calcium orthophosphate, dolomite and the like. The aforesaid inorganicmaterials can be described as "strong abrasives". Organic abrasives suchas urea-formaldehyde, methyl methacrylate melamine-formaldehyde resins,polyethylene spheres and polyvinylchloride are advantageously used toavoid scratching on certain more delicate surfaces, such as plasticsurfaces. Preferred abrasives have a particle size range of about10-1000 microns and are preferably used at concentrations of about 5percent to about 30 weight percent of the hard surface cleaningcompositions.

Thickeners are preferably used to suspend the abrasives. Levels ofthickener difficult to rinse from the cleaned surfaces are undesirable.Accordingly, the level is preferably less than about 2 percent,preferably from about 0.25 to about 1.5 percent. Exemplary thickenersinclude polyacrylates, xanthan gums, carboxymethyl celluloses, swellablesmectite clay, and the like.

Soaps, especially soaps prepared from coconut oil fatty acids are alsooptionally included in the hard surface cleaners.

Optional components include components within the skill in the art toprovide aesthetic or additional product performance benefits. Suchcomponents include perfumes, dyes, optical brighteners, soil suspendingagents, detersive enzymes, gel-control agents, thickeners, freeze-thawstabilizers, bactericides, preservatives, and the like.

The hard-surface cleaning compositions of the invention areadvantageously in the form of liquid compositions, preferably aqueouscompositions, including concentrates, containing as the essentialingredient HEIDA. Preferably a surfactant is also present, morepreferably in a concentration that corresponds to from about 2 to about6 percent surfactant. Concentrated liquid compositions preferablycontain from about 6 to about 10 percent surfactant.

Alternatively, the compositions herein are in the form of creamyscouring cleansers, preferably containing an abrasive material,surface-active agent, and HEIDA.

The cleaning compositions can be packaged in a container that comprisesa means for creating a spray, e.g., a pump, aerosol propellant or sprayvalve. The composition can be thus conveniently applied to the surfaceto be cleaned by conventional means, such as wiping with a paper towelor cloth, without the need for rinsing.

All parts, percentages and ratios herein are by weight unless otherwiseindicated.

The invention will be further clarified by a consideration of thefollowing examples which are intended to be purely exemplary of thepresent invention.

EXAMPLES Example 1

The stepwise procedure for the synthesis of the nitrile precursor toHEIDA:

Synthesis of (I): In a 50 mL round bottom flask was placed 2.0 g (0.033mol) of 2-hydroxyethylamine, 30 mL of water and a magnetic stir bar.While the solution was stirring the glycolonitrile (40% GN, aqueoussolution, 4.67 g, 0.033 mole) was added dropwise. The solution wasstirred at room temperature for 2 h. A ¹³ C NMR indicated that thereaction was complete. ¹³ C NMR (D₂ O): δ 39.0, 52.3, 62.9, 121.6 ppm.

Synthesis of (II): The contents of the solution were carried onto thehydrolysis step without purification by the addition of 2.62 g of 50%NaOH. After stirring at room temperature for 3 h the hydrolysis wascomplete. The solution was brought to a boil to liberate the ammonia.The heating was continued until no further ammonia was detected. ¹³ CNMR (D₂ O): δ 52.7, 54.9, 63.3, 182.5 ppm.

Synthesis of (III): To the solution of II, which was at roomtemperature, was added the glycolonitrile (GN, 40% aqueous, 4.62 g,0.033 mole) dropwise. After stirring for 30 min at room temperature the¹³ C NMR indicated that the reaction was complete. The nitrilointermediate was carried onto the next step without furtherpurification. ¹³ C NMR (D₂ O): δ 45.5, 58.5, 60.8, 61.4, 119.5, 180.5ppm.

Hydrolysis of (III) to (IV): To the aqueous solution of III was added2.62 g of 50% NaOH. After stirring at room temperature for 3 h thehydrolysis was complete. The solution was brought to a boil to liberatethe ammonia. The heating was continued until no further ammonia wasdetected. ¹³ C NMR (D₂ O ): δ 59.7, 61.6, 62.2, 182.7 ppm.

Example 2

The procedure of ASTM D2667 is used to determine the inherentbiodegradablity of HEIDA (IV).

Copper titration value is used to measure the extent of biodegradationof the chelating agents during the procedure. Titration is performedusing ammonium purpurate (indicator for complexometric titration,commercially available from Aldrich Chemical Co., Inc. under the tradedesignation Murexide) as the indicator at approximately pH 8, and usingsodium acetate as buffer. Titration of 2.0 mg HEIDA (0.0105 moles) in100 mL water with 0.01 molar copper chloride gives an endpoint of 1.06mL, representing a 1:1 chelation of copper. Analysis is performed dailyfor a period of 28 days.

Results of the biodegradation screening are given in Table I:

                  TABLE I                                                         ______________________________________                                        Compound    Time for greater than 80% loss of chelation                       ______________________________________                                        NTA (std.)  3 days                                                            HEIDA       5 days                                                            EDTA (std.) greater than 28 days                                              ______________________________________                                    

A control is used to verify the absence of interfering chelatingsubstances in the test.

The results of the biodegradability test show that HEIDA is inherentlybiodegradable and could be expected to be utilized by organisms in amunicipal treatment facility after an acceptable acclimation period.

Example 3

Calcium chelation capacity of HEIDA

The applicability of HEIDA for use in hard surface cleaners, is measuredby the calcium oxalate and calcium carbonate titrations.

For titration with calcium oxalate, between 1 to 2 millimoles of HEIDAis weighed in a 60 mL beaker. After the addition of 30 mL deionizedwater and 5 mL of a 3 % ammonium oxalate solution, the pH is slowlybrought to about 10 by the addition of 20% sodium hydroxide whilestirring. The pH is then adjusted to about 11.6 within sodium hydroxideand the solution is titrated with 0.1 m CaCl₂ to the first permanentturbidity. The chelation valve is then determined from the mL of titrantused based on the following calculation. ##EQU1##

The chelation value is the mg of CaCO₃ that can be chelated by oneactive gram of a chelant, such as HEIDA.

For the carbonate titration, the above procedure is duplicated with 2 mLof 20% sodium carbonate solution replacing the use of the ammoniumoxalate solution.

The turbidity produced in the carbonate titration is due to theformation of 25 calcium carbonate, while the turbidity produced in theoxalate titration is due to calcium oxalate. The results for thetitration of HEIDA in the presence of oxalate and carbonate is comparedwith iminodiacetic acid (IDA) and given in Tables II and IIIrespectively.

                  TABLE II                                                        ______________________________________                                        OXALATE TITRATION                                                             Chelant      Chelation Value                                                  ______________________________________                                        IDA          1                                                                2-HEIDA      206                                                              ______________________________________                                    

                  TABLE III                                                       ______________________________________                                        CARBONATE TITRATION                                                           Chelant      Chelation Value                                                  ______________________________________                                        IDA          5                                                                2-HEIDA      425                                                              ______________________________________                                    

The results from both the oxalate and carbonate titrations show thatHEIDA exhibits a chelation value far superior to IDA, depending on theindicator used. Therefore, for applications requiring calcium control,such as in hard surface cleaners, HEIDA can be used as a morebiodegradable substitute for EDTA.

Other embodiments of the invention will be apparent to those skilled inthe art from a consideration of this specification or practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with the true scope and spiritof the invention being indicated by the following claims.

What is claimed is:
 1. A method for cleaning hard surfaces comprisingcontacting a hard surface with a composition containing 2-hydroxyethyliminodiacetic acid or a salt thereof in an aqueous medium free of anorganic solvent and removing a portion of the composition from the hardsurface.
 2. The method of claim 1 wherein the composition contains fromabout
 0. 1 to about 25 weight percent 2-hydroxyethyl iminodiacetic acidor a salt thereof.
 3. The method of claim 2 wherein the compositioncontains from about 0.3 to about 8 weight percent of a surfactant.